The circadian organization of reproductive behavior in the cricket, Teleogryllus commodus, will be investigated in a terrarium, using time lapse videotape recording. The influence of cold nights on the appearance of premating behavior will be studied by monitoring male singing and female walking to determine the direct or indirect effect of low temperatures. Circadian influence on locomotion in early larval instars will be studied by means of IR-lightbeam devices. Possible circadian regulation of molting rhythms in small populations will be investigated by time lapse photography. Another aim is to study occurrence, size and function of cricket-territories. Local cold pulses will be applied to specific parts of the brain with a cooling probe, in order to locate the timing-device and the intention is to phase-shift singing-activity subsequent to exposure. Loci yielding phase-shifts will be examined histologically. Extracts of the mating factor from the male gonads will be injected into the blood of virgin females, bypassing the sperm storage organ, where the mating factor normally accumulates. The effect of prostaglandins, the endproduct of the enzymatic action of the mating factor, on the neurosecretory system as a mediator for oviposition, will be researched. The number and concentration of Juvenile Hormones in the blood of larvae and adults will be determined with electron capture-gas chromatography.